1. Field of the Invention
The invention is directed to a bellows for coupling a source of acoustic waves, containing an acoustic propagation medium to a living subject.
2. Description of the Prior Art
Acoustic wave sources are employed in medicine, for example, for the disintegration of calculi in the inside of the body of a living subject or for pain therapy. Such a source of acoustic waves can, for example, include an electromagnetic pressure pulse source, an acoustic propagation medium, an acoustic lens or a concave mirror as well as a bellows for coupling the source of acoustic waves to the body of a the subject to be treated. Using the electromagnetic pressure pulse source, pressure pulses are introduced into the acoustic propagation medium, the pressure pulses propagating in the acoustic propagation medium and being focused by the acoustic lens or the concave mirror. The introduction of the focused acoustic waves into the body of the subject ensues via the acoustic propagation medium and the bellows for coupling to the subject.
Conventionally, acoustic waves generated with a source of acoustic waves are not shaped further after passing through the acoustic lens and before entry into the body of the subject. When a surface between the acoustic lens and the body surface of the subject into which the acoustic waves are introduced is considered perpendicular to the main propagation direction of the acoustic waves, one finds that the acoustic waves or the field of acoustic waves is not homogeneously distributed within its −6 dB zone. Instead; zones of very high positive or negative pressure that can lead to negative physical effects on the life form, particularly to irritation of the skin of the subject, are located, for example, close to the middle axis of the source of acoustic waves.
German OS 195 34 809 discloses an apparatus for treating body tissue and for the disintegration of body calculi by means of acoustic energy. In order to avoid undesired deviations from the straight-line propagation of the acoustic waves or from the planned propagation of the acoustic waves upon transition from the apparatus to the body tissue, among the items proposed is to shape the geometry of the boundary surface such that deviations do not ensue, or ensue in controlled fashion. For example, planar, spherical or other boundary surfaces shaped in a controlled fashion can be generated by the pressing force of appropriately shaped applicators.
German OS 33 12 014 discloses an apparatus for the non-contacting disintegration of calculi in the body of a subject using shock waves. The shock waves are coupled into the body of a patient with a coupling member that is preferably elastically deformable. The focus of the shock waves can be set to the treatment region within certain limits by deformation of the coupling member. Disks that are composed of the same material as the coupling members can be additionally attached to the coupling member for expanding the focus adjustment possibilities.